11(1)A penalty under this Schedule must be paid—U.K.
(a)before the end of the period of 30 days beginning with the date on which the notification under paragraph 9 was issued, or
(b)if a notice of appeal against the penalty is given, before the end of the period of 30 days beginning with the date on which the appeal is determined or withdrawn.
(2)A penalty under this Schedule may be enforced as if it were income tax charged in an assessment and due and payable.